Twenty Years' War

The Twenty Years' War was a military conflict between the Republic of Venice and the Byzantine Empire that was waged in the Balkans region. Due to Venetian expansion in the Balkans, the Byzantines preemptively declared war on Venice and sent an army to besiege Durazzo on two occasions. Both of these attempts failed and the Venetians captured the city of Nicosia on the Isle of Cyprus from them in 1128, the last action of the war. That year, the Byzantine Greeks made peace with the Venetians.

Background
After the fall of the Roman Empire, the Byzantine Empire remained the dominant military power in Europe. However, as the years passed by it was overshadowed by the Holy Roman Empire and was slowly conquered by The Turks from Central Asia. By 1080 it included only Greece and the western parts of Asia Minor, and was trapped in an increasingly smaller area of land. In Italy, the Republic of Venice quickly expanded its trade empire to former Byzantine possessions such as rebel states along the Dalmatian coast and the Levant, and the Byzantines could only watch as the Venetians took over more lands and gain more money by the minute.

The Byzantines made a trade agreement with the Venetians, in hopes of prospering through commerce. Doge Domenico Selvo was intent on keeping his empire while taking over northern Italy from the Duchy of Milan and expanding his empire against the Heretics of the Levant. Emperor Alexius I of Byzantium did not want to let the Venetians gain the upper hand in the political situation in Europe, so he gambled on a preemptive strike in 1108. He declared war on Venice, breaking his trade agreement, but he did not make any moves until the 1120s. Alexius mobilized small armies in The Balkans, using the excuse of protecting his merchants in the Balkans and fighting a trade war against Venice. In 1126, his army under Volkanos Metochites marched out.

War
The Venetian stronghold of Durazzo, defended by Barbus Selvo and Alessandro Selvo, bolstered its defenses to face the invading Byzantine army under the nobleman Metochites. Although the Byzantines had a large army, the Venetians exploited poor leadership in their ranks and assaulted, pushing back the Byzantines and inflicting heavy losses. Metochites withdrew to northern Greece, letting the Venetians keep control of Albania and their prewar territories.

Alexius' failure to take control of Durazzo was a blow to Byzantine morale and a morale boost to the Venetians, as Barbus Selvo became a hero. Undeterred, he dispatched a smaller army to finish what Metochites had started. Just a year after the invasion of Durazzo, the Byzantines were back at the gates, but faced an even larger Venetian army, as Barbus Selvo had mustered troops for a planned march south on the Byzantine city of Corfu in Greece. Once more, the Byzantines were repelled from their assault with only light casualties on the Venetian side.

Doge Domenico the Honourable planned a counteroffensive, recommended to take control of Nicosia by his Council of Nobles. Having taken control of Armenia in Asia Minor and having secured his position in the Levant by allying with The Turks, Selvo set out from Armenia on ships with a large army, and when he landed in Cyprus, he recruited Armenian Cavalry and other mercenaries to bolster his armed forces. He encircled the city and constructed ladders, preparing to assault the city when the siege engines were finished. In 1128, after a two-year siege, he assaulted the defenses and captured the city from the Byzantines. The Isle of Cyprus proved to be a fruitful possession, as it provided high trade income to Venice as well as a good shipyard.

Peace and Aftermath
Princess Anna Comnenus was dispatched to the city of Durazzo to make peace with Venice. Barbus Selvo accepted the peace treaty and also made a trade agreement. By 1132 the Venetians and Byzantines had increased relations so far that they forged a military alliance, promising to defend each other's existence on Earth. For the world, Venice had proven itself an adept military power, and the Byzantine Empire continued its steep decline.